Merge branch 'docs-clarify-primary-identifier' into 'master'

Clarify docs for primary vulnerability identifier

See merge request gitlab-org/gitlab!43235

doc/development/integrations/secure.md

@@ -374,12 +374,16 @@ which is shared by the analyzers that GitLab maintains. You can [contribute](htt
 new generic identifiers to if needed. Analyzers may also produce vendor-specific or product-specific
 identifiers, which don't belong in the [common library](https://gitlab.com/gitlab-org/security-products/analyzers/common).
 
-The first item of the `identifiers` array is called the primary identifier.
+The first item of the `identifiers` array is called the [primary
+identifier](../../user/application_security/terminology/#primary-identifier).
 The primary identifier is particularly important, because it is used to
 [track vulnerabilities](#tracking-and-merging-vulnerabilities) as new commits are pushed to the repository.
 Identifiers are also used to [merge duplicate vulnerabilities](#tracking-and-merging-vulnerabilities)
 reported for the same commit, except for `CWE` and `WASC`.
 
+Not all vulnerabilities have CVEs, and a CVE can be identified multiple times. As a result, a CVE
+isn't a stable identifier and you shouldn't assume it as such when tracking vulnerabilities.
+
 ### Location
 
 The `location` indicates where the vulnerability has been detected.